Piston locking device



E. P. SUNDHOLM PISTON LOCKING DEVICE Aug. 2, 1955 2 Sheets-Sheet 1 Filed Jan. 31, 1950 INVENTOR. [ow/N F. J'I/A/DHOLM BY @MXW 2 Sheets-Sheet 2 Aug. 2, 1955 E. P. SUNDHOLM I PISTON LOCKING DEVICE Filed Jan. 51, 1950 \lflllllll MN Nm 1 U R. Om MN NW Y 4 m5. f mv vw l P. M 4.1 mm W m w I m \K 1 mN WN PM W S Hrromvz v United States Patent PISTON LOCKING DEVICE Edwin P. Sundholm, Albert City, Iowa Application January 31, 1950, Serial No. 141,417 12 Claims. (Cl. 222386) The present invention relates to certain new and useful lubricating equipment and more particularly to a new and improved grease-gun.

An object of the present invention is to provide means for locking a spring-urged piston at the rear of a greasegun barrel.

Another object of the present invention is to provide detachable locking-means for securing a piston at the rear of a grease-gun barrel.

Still another object of the present invention is to provide cooperating means between the grease-gun barrel and a piston disposed therewithin whereby to detachably secure the piston at one end of the barrel.

Further objects will be apparent by reference to the appended specification, claims and drawings.

For the purpose of illustrating the invention, there is shown in the accompanying drawings one form thereof which is at present preferred, although it is to be under stood that the various instrurnentalities of which the invention consists can be variously arranged and organized and that the invention is not limited to the precise arrangements and organizations of the instrumentalities as herein shown and described.

Referring to the drawings wherein like reference characters indicate like parts:

Figure 1 represents a perspective view of a grease-gun embodying the present invention, viewed generally from the top and front-end thereof.

Figure 2 represents a perspective view of the greasegun shown in Figure l with the high-pressure head and hand-lever removed therefrom and viewed generally from the top and rear thereof.

Figure 3 represents a side-elevational view, partly in section, of the grease-gun of Figures 1 and 2.

Figure 4 represents a vertical cross-sectional view of the rear end of a grease-gun embodying the present invention, similar to the view of Figure 3, but on a much enlarged scale so as more clearly to reveal the details of construction thereof.

Figure 5 represents a perspective View, partially in section, of the locking-cup of the present invention viewed generally from the top thereof.

Figure 6 represents a perspective view of the lockingcup of the present invention viewed generally from the bottom thereof.

Figure 7 represents a top of Figures 5 and 6.

Figure 8 represents a perspective view of the rear face of the piston showing the cooperating locking means thereon.

Figure 9 represents a fragmentary cross-sectional view through the grease-gun piston showing a modified form of locking-collar or pronged collar.

Figure 10 represents a fragmentary cross-sectional view along line Ill-10 of Figure 9.

Grease-guns of the general type contemplated by the present invention have long been known in the art and may include push-type or lever-type guns having a barrelplan view of the locking-cup portion with a fluid-tight, reciprocable piston therein. A lever-type grease-gun thus contemplated is shown in the drawings, and is similar to the grease-gun disclosed in Sundholm Patent 2,218,363 which issued October 15, 1940. The grease-gun includes a barrel 10 having a piston 11 reciprocable therein in sliding: and fluid-tight contact therewith, and a high-pressure head 12 or similar discharge nozzle secured at one end thereof. A pistonrod 13 fits slidingly within the piston 11 and has a pin or abutment 14 at one end adapted to cooperate with said piston whereby to reciprocate the piston within the barrel 10. The other end of the piston-rod 13 projects beyond the rear end of the barrel through an aperture 15 in a cap-member 16 and has a handle 17 secured thereto.

The piston 11 may be formed of a plurality of discs such as discs 18 and 19 with the annular synthetic-rubber sealing-member 20 secured around the periphery thereof. The shank of a locking screw 22 passes through an aperture 21 in the center of the plates 18 and 19. Hexagonal depressions 23 in each of the plates 18 and 19 are adapted to interlock with one another so as to prevent rotary motion between said plates, and the depression in the plate 18 is adapted to receive the hexagonal head 24 of the screw 22. A locking-collar 25 threadedly secured on the shank of the screw 22 holds the plates 18 and 19 together and secures the screw 22 thereto.

A transverse slot 26 and an axially-extending slot 27 in the head 24 of the screw 22 are adapted to receive the pin 14 of the piston-rod 13. Thus, by means of the pin i4 and the slots 26 and 2'7, the forward end of the piston-rod 13 may be detachabiy secured to the piston 11 so that the piston may be reciprocated within the barrel 10 by the piston-rod 13 and the handle 17.

A compression spring 21*; is disposed between one side of the piston 11 and the rear cap-member 16 to urge the piston 11 forwardly within the barrel at all times. The spring 22% is highly desirable because, with the piston, it exerts pressure upon the lubricant in the barrel All and forces the lubricant through the forward end of the barrel into the hlgh-pressure head 12.

When it is desired to fill the grease-gun with lubricating fluid, the high-pressure head 12 is removed from the barrel l0 and the forward end of the barrel is inserted into a container of grease (not shown) and the pistonrod 11 is drawn rearwardly within the barrel to by a rearward pull on the handle 17 and piston-rod 1:). the vacuum created within the barrel 10 m from of the retracted piston 11 draws lubricant fluid into the barrel, whereupon the barrel may be removed from the supply of lubricant and the high-pressure head 12 replaced. Then the handle 17 may be released and the spring 28 will urge the piston 11 and the lubricant forwardly so as to rorce the lubricant into the high-pressure head 12. Thereafter the grease-gun may be operated in the customary manner.

As will be appreciated by those skilled in the art, it is difficult to hold the retracted piston 11 at the rear of the barrel 10 against the force or the spring 26 (after the barrel has been lined with lubricant) while the highpressure head is being secured to the forward end or the barrel. Thus 1 provide the locking means of the present invention to detachably secure the piston 11 at the rear of the barrel against the action of the spring 28, leaving both hands of the operator free to manipulate and replace the high-pressure head on the barrel.

The lOCKlllg means of the present invention includes a generally hat-shaped locking-cup 29 having a body portion 30 with a liuted flange 31 at one end thereof. the outer diameter of the fluted flange 31 is the same as the outer diameter of the barrel 10. Thus the locking-cup 29 may be secured at the rear end of the barrel 10 between the rear edge 32 thereof and the inner surface of the cap- 3 member 16, when said cap-member is screw-threadcdly secured to the barrel, as is shown particularly in Figure 4.

A plurality of depressions 33 in the cap-member 16 are adapted tov enter the undulations of the fluted flange 31 whereby to interlock the locking-cup 29 and the capportion 16 and to prevent rotary motion therebe'tween when the locking-cup 29 is securely held against the rear edge 32 of the barrel 10.

Thus, the locking-cup 29 is detachably and yet rigidly and securely held at the rear of the barrel 10, with one end of the compression spring 28 bearing against the underside of the fluted flange 31.

The bottom 34 of the locking-cup 29 has a generally central aperture 35 therein with a plurality (3 being shown) of radially inwardly extending lugs 36 therein. The inner edges 37 of the lugs 36 define portions of a circular aperture which is co-axial with the body portion 3'3 of the cup 29 and is large enough to permit the packinggland 38 on the piston 11 to pass therethrough when the piston is drawn rearwardly within the barrel 10.

The locking-collar on the piston 11 has a plurality (3,)of radially outwardly-extending fingers 39 thereon whichare, adapted to pass into the locking-cup 29 through the notches 40 between the lugs 36. Thus, the outer edges 41, of the fingers 39 define portions of ,a circle having a diameter less than the diameter of the circle defined by the edges 42 of the notches 40 but greater than the diameter of the circle defined by the edges 37 of the lugs. 36. Moreover, the width of the, fingers 39 is less than the arcuate dimension of, the notches 40 whereby to permit the fingers 39 on the locking-collar 25 to pass therethrough into the interior of the body portion of the lockingcnp 29.

An upstanding abutment 43 is disposed on each of the lugs 36 along one edge thereof, as shown particularly in Figures 4 and 5.

Thus, when the piston 11 is drawn rearwardly within the barrel 10, the locking-collar 25 and the fingers 39 thereon may pass through the aperture in the bottom 34 of the locking-cup 29(with the fingers 39 aligned with the notches 4.0 and with the lugs 36 axially aligned with the spaces between the fingers 39)., After the fingers 39 have cleared the inside surface of the bottom 34. (with the. rear face of the plate 19 on the piston 11 adjacent or in contact. with. the outer surface of the, bottom 34), a rotarytwist (clockwise when viewed from the rear end of the barrel 10) on the handle 17 will cause the piston 11 to rotate slightly (the pin 14 being engaged in the slot 27 of the piston 11) until thefingers 39 strike the abutments 43 and are thus axially aligned with the lugs 36 in the. locking-cup. .29.

Thereupon, if the handle 17 is released, the spring 28 will urgethe piston 11 forwardly bringing the lugs .36 and the fingers 39 into engagement whereby to. prevent the forward movement of the piston 11. Thus the handle 17 can be released with the piston 11 locked in a rearward position within the barrel 10, leaving both hands of the operator free to manipulate the barrel and replace the high-pressure head 12 thereon.

After the gun has been filled with grease and the highpressure head replaced, the piston-rod 13 and the handle 17 may be rotated slightly (counterclockwise when viewed from the rear of the barrel) so as to align the pin 14 with the. slot 27. Thereafter the handle may be pushed forwardly so, as to disengage the .pin 14. from the piston 11 and, with the; piston still securely locked at the rear of the barrel, the handle 17 and. the piston-rod. 13. may be telescoped within the barrel 10. to reduce the; external dimension. of the grease-gun.

If it is desired to. disengage; the piston from the locking means so that the spring .28v may urge it forwardly within the. barrel, the piston-rod 13. may be rotated counterclockwise (when viewed from the rear end) without disengaging the, pin 14 from the slot 26. so that a. continued counterclockwiseturning of thepiston-rod 13 and the piston 11 will cause the fingers 39 to rotate with respect to the lugs 36 and bring the fingers 39 into alignment with the notches in the locking-cup 29 whereupon the spring 28 may urge the piston forwardly and bring the fingers 39 out of engagement with the locking cup 29. Thus the piston may be urged forwardly against the lubricant within the barrel 10 compressing it forwardly and forcing it toward the high-pressure head 12.

Thereafter if it is desired to telescope the handle 17 and the piston rod 13 within the barrel, the pin 14 may be aligned with the slot 27 and the handle urged forwardly so as to telescope the piston-rod within the barrel.

Thus I have provided means for detachably securing a piston at the rear of a barrel of a grease-gun. The locking means includes the locking-collar 25 with associated fingers 39 and the locking-cup 29. It is to be noted that the locking-cup 29 may be independent of the rear cap member 16. Although the depressions 33 in the rear cap 16 are desirable because they engage the undulations of the fluted flange 31 and prevent rotary motion of the lock- ..ing-cup 29, the undulations in the flange 31 and the depressions 33 may be eliminated if the flange 31 is securelyfastened between the rear edge 32 of the barrel 10 and the rear cap-member 16.

The locking means of the present invention is easily operated and is an effective means of detachably securing the piston at the rear end of the barrel against the force of the compression spring 28. Moreover, it is inexpensive to manufacture.

An alternate form of locking-collar or pronged collar 25-41 is shown in Figures 9 and 10. In this embodiment the screw 22-11 has a threaded portion 45 which is shorter in length than the threaded portion of the screw 22. A cylindrical portion 46 intervenes the threaded portion 45 and the rear surface of the disc 19, with a groove 47 between the cylindrical portion 46 and the threads 45.

A collar 25-a, similar to the collar 25 but having a smooth internal bore therein rather than the threaded bore of the collar 25, may be press-fitted on to the cylindrical portion 46 to hold the discs 18 and 19 of the piston 11 in place. After the collar 25-a is in positon, as shown in Figure 9, the upper edges 48 thereof which intervene the fingers 39 may be crimped or staked or otherwise pressed inwardly into the groove 47 whereby to lock the collar 25-a to the screw 22-a. Thus,'the locking-collar 25-a functions in the same manner as the locking-collar 22, but the internal threads on the bore thereof are eliminated.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore desired that the present embodiment be considered in all respects as illustrative and not restrictive, reference being had to the appended claims rather than to the foregoing description to indicate the scope of the invention.

Having thus described my invention, what I claim as.

new and desire to protect by Letters Patent is the following:

1. A grease-gun having a barrel, a cap-member at one end of said barrel, a piston in said barrel, a piston-rod slidable through said piston and said cap-member, lockingmeans for securing said piston at one end of said barrel, said locking-means including a cup having a radiallyextending flange secured at one end of said barrel by said cap-member, an aperture in the bottom of said cup with at least one radially-extending lug therein, at least one radially-extending finger fixedly and non-rotatably secured on said piston adapted to pass through the aperture in said cup when not aligned with said lug and thereafter adapted to be rotated into alignment with and engagement with said lug.

2. A grease-gun having a. barrel, a cap-member at one end of said barrel, a piston in said barrel, a piston-rod slidable through said piston and saidcap-member, lockingmeans for securing said piston at one end of said barrel,

said locking-means including a cup having a radiallyextending flange secured at one end of said barrel by said cap-member, an aperture in the bottom of said cup with at least one radially-extending lug therein, said lug having an upstanding abutment along one edge thereof, at least one radially-extending finger fixedly and non-rotatably secured on said piston adapted to pass through the aperture in said cup and thereafter adapted to be rotated into alignment with and engagement with said lug.

3. A grease-gun having a barrel, a cap-member at one end of said barrel, a piston in said barrel, a piston-rod slidable through said piston and said cap-member, lockingmeans for securing said piston at one end of said barrel, said locking-means including a cup having a radiallyextending flange secured at one end of said barrel by said cap-member, an aperture in the bottom of said cup with at least one radially-extending lug therein, a lockingcollar fixedly and non-rotatably secured on said piston, said locking-collar having at least one radially-extending finger adapted to pass through the aperture in said c'up and thereafter adapted to be rotated into alignment with and engagement with said lug.

4. A grease-gun having a barrel, a cap-member at one end of said barrel, a piston in said barrel, a piston-rod slidable through said piston and said cap-member, lockingmeans for securing said piston at one end of said barrel, said locking-means including a cup having a radiallyextending flange secured at one end of said barrel by said cap-member, a plurality of radial grooves in said flange and a plurality of indentations in said cap-member adapted to enter said grooves and interlock said flange and said cap-member and prevent rotation thereof, an aperture in the bottom of said cup with at least one radiallyextending lug therein, at least one radially-extending finger fixedly and non-rotatably secured on said piston adapted to pass through the aperture in said cup and thereafter adapted to be rotated into alignment with and engagement with said lug.

5. A grease-gun having a barrel, a cap-member at one end of said barrel, a piston in said barrel, a piston-rod slidable through said piston and said cap-member, lockingmeans for securing said piston at one end of said barrel, said locking-means including a cup having a radiallyextending flange secured at one end of said barrel, means on said cap to prevent rotation between said cup and said barrel, an aperture in the bottom of said cup with at least one radially-extending lug therein, at least one radiallyextending finger fixedly and non-rotatably secured on said piston adapted to pass through the aperture in said cup and thereafter adapted to be rotated into alignment with and engagement with said lug.

6. Locking-means for securing a piston at one end of the barrel of a grease-gun, said locking-means including a cup having a radially-extending flange non-rotatably secured at one end of the barrel, an aperture in the bottom of said cup with at least one radially-inwardly extending lug therein, at least one radially-outwardly extending finger fixedly and non-rotatably secured to the piston and adapted to pass through the aperture in said cup and thereafter adapted to be rotated into alignment with and engagement with said lug.

7. Locking-means for securing a piston at one end of the barrel of a grease-gun, said locking-means including a cup having a radially-extending flange non-rotatably secured at one end of the barrel, an aperture in the bottom of said cup with at least one radially-inwardly extending lug therein, said lug having an upstanding abutment along one edge thereof, at least one radially-extending finger fixedly and non-rotatably secured to the piston and adapted to pass through the aperture in said cup and thereafter adapted to be rotated into alignment with. and engagement with said lug.

8. Locking-means for securing a piston at one end of the barrel of a grease-gun, said locking-means including a cup having a radially-extending flange non-rotatably secured at one end of the barrel, an aperture in the bottom of said cup with at least one radially-extending lug therein, a locking-collar fixedly and non-rotatably secured to the piston, said locking-collar having at least one radially-extending finger adapted to pass through the aperture in said cup and thereafter adapted to be rotated into alignment with and engagement with said lug.

9. Locking-means for securing a piston at one end of the barrel of a grease-gun, said locking-means including a cup having a radially-extending flange secured at one end of the barrel, means to prevent rotation between said cup and the barrel, an aperture in the bottom of said cup with at least one radially-inwardly extending lug therein, at least one radially-extending finger fixedly and nonrotatably secured to the piston and adapted to pass through the aperture in said cup and thereafter adapted to be rotated into alignment with and engagement with said lug.

10. A grease-gun having a barrel, a cap-member secured at one end of said barrel, a piston in said barrel, a piston-rod slidable through said piston and said capmember, locking means for detachably securing said piston at one end of said barrel, said locking-means com prising a hat-shaped cup having an undulating flange secured between said barrel and said cap-member, at least one indentation in said cap-member adapted to enter said undulations and interlock said cup, cap-member and barrel, an aperture in the bottom of said cup, at least one lug on said cup extending radially into said aperture, at least one finger fixedly and non-rotatably secured on said piston adapted to enter said cup through said aperture and to be thereafter aligned with and brought into engagement with said lug.

11. A grease-gun having a barrel, a cap-member secured at one end of said barrel, a piston in said barrel, a piston-rod slidable through said piston and said capmember, locking-means for detachably securing said piston at one end of said barrel, said locking-means comprising a locking member secured between said barrel and said cap-member and having at least one locking-lug thereon, said piston having at least one finger, said finger being fixedly and non-rotatably secured to said piston and adapted to be rotated into alignment with and engagement with said lug when said piston is at the rear end of said barrel whereby to lock said piston at one end of said barrel.

12. Locking-means for detachably securing a piston at one end of the barrel of a grease-gun, said locking-means comprising a member secured at one end of the barrel and having an aperture with at least one radially-inwardly extending locking-lug thereon, at least one locking-finger secured to the piston of the grease-gun, and adapted to be rotated into alignment with and engagement with said lug when the piston is at the rear end of the barrel whereby to lock the piston at one end of the barrel.

References Cited in the file of this patent UNITED STATES PATENTS 1,794,131 Zabriskie Feb. 24, 1931 2,124,077 Ostendorf July 19, 1938 2,124,138 Eastman July 19, 1938 

